The Effects of Oat and Barley Consumption on Inflammation and the Gut Microbiome

by | Oct 25, 2024 | 2024, Recent Articles, Whole Grains

Written by Harold Oster, MD. Results suggest that consumption of oats and barley may be anti-inflammatory and have a favorable effect on the gut microbiome.

MIcrobiome - probioticsChronic inflammation and the oxidative stress that follows can lead to the onset of numerous conditions, including diabetes, heart disease, neurological disease, and cancer1. The gut microbiome plays an important role in human health, influencing the risk of multiple chronic diseases2. Intestinal bacteria in a healthy microbiome ferment dietary fiber and produce short-chain fatty acids, which are anti-inflammatory and have various metabolic benefits3. The consumption of whole grains is beneficial to human health, reducing the risk of cancer, heart disease, diabetes, and gastrointestinal disorders. Barley and oats have especially high levels of beta-glucan, a soluble fiber responsible for many of the benefits of whole grains4.

María-Engracia Cortijo-Alfonso et al. performed a literature search for randomized controlled studies that evaluated the effects of whole-grain barley, oats, or beta-glucan on inflammatory markers or gut microbiota composition. Participants in the studies were adults who were not taking medications regularly and had not recently taken antibiotics. Included in the search were the following inflammatory markers: C-reactive protein,5 lipopolysaccharide-binding protein6, tumor necrosis factor, and various interleukins7.

The authors noted the following:

  • Based on exclusion criteria, sixteen studies were included in the review.
  • Three studies were performed on healthy young adults, five on healthy older adults, and six on individuals with metabolic abnormalities such as diabetes. One study enrolled individuals with gastritis, and another included only polypectomized patients.
  • There were a total of 1091 participants in the studies.
  • The studies in young adults only tested barley, and there was no apparent effect on inflammatory markers.
  • One study in older adults showed a benefit of oat beta-glucan on levels of the inflammatory marker gamma interferon8 after influenza vaccination. There was no apparent effect on the other inflammatory markers tested. The other studies in healthy older adults showed no effect on inflammatory markers.
  • Four studies in those with metabolic abnormalities evaluated participants for the effects of oats or barley on inflammatory markers. Three of these studies showed a reduction in inflammation in the intervention group.
  • Twelve articles in the review evaluated participants for the effect of barley or oats on gut microbiota. There was no consistent effect on specific intestinal bacterial composition. However, several studies showed changes consistent with an improved gut microbiome, including an increase in Bacteroides species9, an increase in bacterial diversity2, and an increase in short-chain fatty acid production3.

Results suggest that the consumption of oats and barley may have a favorable effect on the gut microbiome. In older individuals and those with metabolic disorders, there may be a favorable effect on inflammation. The review’s limitations include a small number of studies, studies using different designs, and possible selection bias.

Source: Cortijo-Alfonso, María-Engracia, María-Paz Romero, Alba Macià, Silvia Yuste, Marian Moralejo, Laura Rubió-Piqué, and Carme Piñol-Felis. “Effect of barley and oat consumption on immune system, inflammation and gut microbiota: a systematic review of randomized controlled trials.” Current Nutrition Reports (2024): 1-16.

© The Author(s) 2024

Click here to read the full text study.

Posted October 24, 2024.

Harold Oster, MD graduated from medical school in Miami, Florida in 1992 and moved to Minnesota in 2004. After more than 25 years of practicing Internal Medicine, he recently retired. Dr. Oster is especially interested in nutrition, weight management, and disease prevention. Visit his website at haroldoster.com.

References:

  1. Furman D, Campisi J, Verdin E, et al. Chronic inflammation in the etiology of disease across the life span. Nat Med. Dec 2019;25(12):1822-1832. doi:10.1038/s41591-019-0675-0
  2. Hills RD, Jr., Pontefract BA, Mishcon HR, Black CA, Sutton SC, Theberge CR. Gut Microbiome: Profound Implications for Diet and Disease. Nutrients. Jul 16 2019;11(7)doi:10.3390/nu11071613
  3. Xiong RG, Zhou DD, Wu SX, et al. Health Benefits and Side Effects of Short-Chain Fatty Acids. Foods. Sep 15 2022;11(18)doi:10.3390/foods11182863
  4. P NPV, Joye IJ. Dietary Fibre from Whole Grains and Their Benefits on Metabolic Health. Nutrients. Oct 5 2020;12(10)doi:10.3390/nu12103045
  5. Sproston NR, Ashworth JJ. Role of C-Reactive Protein at Sites of Inflammation and Infection. Frontiers in immunology. 2018;9:754. doi:10.3389/fimmu.2018.00754
  6. Zweigner J, Schumann RR, Weber JR. The role of lipopolysaccharide-binding protein in modulating the innate immune response. Microbes Infect. Mar 2006;8(3):946-52. doi:10.1016/j.micinf.2005.10.006
  7. Al-Qahtani AA, Alhamlan FS, Al-Qahtani AA. Pro-Inflammatory and Anti-Inflammatory Interleukins in Infectious Diseases: A Comprehensive Review. Trop Med Infect Dis. Jan 4 2024;9(1)doi:10.3390/tropicalmed9010013
  8. Kak G, Raza M, Tiwari BK. Interferon-gamma (IFN-γ): Exploring its implications in infectious diseases. Biomol Concepts. May 30 2018;9(1):64-79. doi:10.1515/bmc-2018-0007
  9. Zafar H, Saier MH, Jr. Gut Bacteroides species in health and disease. Gut Microbes. Jan-Dec 2021;13(1):1-20. doi:10.1080/19490976.2020.1848158